The result of the past six years of program (sponsored by NIH) indicate that the choline containing pneumococcal teichoic acids provide one of the systems of choice to probe into the functions and replication of these ubiquitous bacterial surface components. The key central conclusion that has emerged from our studies so far is that teichoic acids exert many of their physiological effects via control of the activity of cellular autolysins. For this reason, the program outlined here--in addition of being a continuation of previous studies--has some new points of emphasis. The main problems of the new program are: (1) Purification of autolysin. (2) Controls of autolysin activity (on substrate level; by factors; on the level of enzyme assembly). (3) The nature of wall growth zone. (4) Biosynthetic experiments. (5) Role of autolysin in phage infection.